1. Field of the Invention
The present invention relates generally to the fabrication of magnetic heads for hard disk drives, and particularly to the fabrication of electrical leads within the read head portions of such magnetic heads.
2. Description of the Prior Art
As is well known, the read head portion of a magnetic head is fabricated utilizing thin film deposition techniques on an upper surface of a wafer substrate. In fabricating a typical read head, a plurality of layers and structures are deposited that generally include a first magnetic shield, an insulation layer, magnetoresistive sensor layers, and magnetic hard bias elements. Electrical leads, a second insulation layer and a second magnetic shield are then deposited. Further magnetic head components such as write head structures are then fabricated to complete the magnetic head.
As areal data storage densities increase and read gap dimensions decrease, the thickness of the second insulation layer has been decreased and the thickness of the electrical leads has also preferably been decreased in order to prevent electrical shorts through the second insulation layer to the second magnetic shield. However, any reduction in the electrical lead thickness must be accomplished while providing reasonable operating currents for the sensor, and increasing the conductivity of the electrical leads allows for the same current to be carried in thinner leads. Thus, higher conductivity electrical lead structures are important for continued increases in areal data storage density. This invention is directed towards a method for increasing the conductivity of the electrical lead material through modification of its crystalline microstructure.
Methods for increasing lead conductivity have relied on using higher conductivity lead metallurgies based on high conductivity metals such as Au. However, Au is known to have a smearing problem upon definition of the lead in the row fabrication process. Also, Au, unless great care is taken in its heat treatment with Ta capping layers, can become thermally unstable by growing nodules that short out the lead to the second magnetic shield.